Nissan Oem O2 Sensor SR20DET S13 Fat Type

Changing out your old sensor to a new one usually would improve gas mileage. For S13 models, there's 2 type of O2 sensors. There is the Large (FAT) (blacktop) and Small (Skinny) (Redtop) type, both have 3 wires. Images shown above are for the fat blacktop type. Either model will work on the engines, the only difference is the thread size.